1. Field of the Invention
The present invention relates to an apparatus for aligning electronic component chips, which is adapted to align along a prescribed direction a plurality of electronic component chips (including electrical parts such as passive and active parts, finished chip components and partially fabricated components). More particularly, it relates to an improvement for smoothing movement of a plurality of electronic component chips within such an apparatus for aligning electronic component chips.
2. Description of the Background Art
A technique for smoothing movement of a plurality of electronic component chips in such an apparatus for aligning electronic component chips as described above has been described in Japanese Patent Application No. 63-335107 and Japanese Patent Application No. 63-335108 (both corresponding to USSN 458897, GB 2226547A and DE 3942996A1) filed by the applicant (assignee) of the present application.
The applicant of the present application has proposed a cassette storing electronic components, which is advantageously employed for supplying electronic component chips to a chip supplying apparatus in Japanese Patent Application No. 62-96925 (corresponding to EP 0288277A2 and USSN 184112).
The aforementioned cassette storing electronic component chips basically comprises a plurality of electronic component chips, a case having an internal storage space for storing the electronic component chips and an outlet communicating with the internal storage space for discharging the electronic component chips, and an openable closure for closing the outlet. An electronic component chip manufacturer can directly use such a cassette storing electronic component chips as a packaging mode which is applicable to transportation of electronic component chips, while a user of electronic component chips can directly mount the cassette on a chip mounting apparatus for supplying a plurality of electronic component chips one by one to a chip mounting station.
FIG. 8 is a sectional view illustrating a chip mounting step carried out through such a cassette 1 storing electronic component chips (which is shown in phantom lines). The cassette 1 is directly mounted on a hopper 2 of a chip mounting apparatus. More specifically, the cassette 1 is fixed to the hopper 2 so that its outlet faces an opening 3 of the hopper 2, and a closure of the cassette 1 is opened to supply a plurality of electronic component chips 4, which have been stored in an internal storage space of the cassette 1, into the hopper 2 from the outlet.
The hopper 2 is generally inclined at an angle 5 of inclination of about 45.degree., for example. The electronic component chips 4 supplied into the hopper 2 first flow into a large chamber 6 and then enter a small chamber 7, to finally reach an aligning passage 8. This aligning passage 8 is adapted to guide and move the plurality of electronic component chips 4 in a state aligned with each other along a prescribed direction. In order to achieve this function, sectional dimensions of the aligning passage 8 are selected in relation to the sectional dimensions of each electronic component chip 4.
The small chamber 7 is communicated with the aligning passage 8 and is formed in the vicinity of an inlet 9 of the aligning passage 8, defining a space having larger sectional area than that of the aligning passage 8.
FIG. 9 is an enlarged perspective view showing the structure provided between the small chamber 7 and a portion close to the inlet 9 of the aligning passage 8. As understood from FIGS. 9 and 8, the small chamber 7 has one wall surface 11 which is flush with a wall surface 10 defining the inlet 9 of the aligning passage 8. The wall surface 11 extends to the larger chamber 6 providing a bottom surface of a groove.
A blowing passage 12 is provided in a portion near the inlet 9 of the aligning passage 8, in order to introduce compressed air from the exterior in an intermittent manner, for example. The compressed air introduced through the blowing passage 12 blows off and stirs the electronic component chips 4 approaching the inlet 9 of the aligning passage 8.
Thus, the plurality of electronic component chips 4 supplied from the cassette 1 pass through the large chamber 6 and the small chamber 7 to approach the aligning passage 8, and are aligned along a prescribed direction to enter the inlet 9. Then the electronic component chips 4 are guided by the aligning passage 8 and discharged from the outlet 13. The electronic component chips 4 discharged from the outlet 13 are aligned in the prescribed direction. Thus, the chip mounting step can be efficiently carried out by retaining the electronic component chips in the aligned state.
FIG. 9 shows the hopper 2 with a side plate forming a front side wall surface removed. Namely, referring to FIG. 9, actually a side plate, not shown, is positioned along the wall surface denoted by the reference numeral 14, and by this side plate, the small chamber 7, the aligning passage 8 and the large chamber 6 are closed. aligning passage 8 and the large chamber 6 are closed. Therefore, the space in the small chamber 7 has a cross-directional dimension denoted by the reference numeral 15.
FIG. 9 shows three electronic components 4 which are horizontally aligned with each other. The total of the cross-directional sizes of these electronic component chips 4 accidentally coincides with the cross-directional size 15 of the space defined in the small chamber 7. Thus, these electronic component chips 4 unmovably butt against each other between the wall surfaces defining the cross-directional size 15. Once such a phenomenon, that is, the so-called "bridge phenomenon" takes place, it is difficult to separate the electronic component chips 4 which are in such series from each other, even if compressed air is introduced through the blowing passage 12.
The aforementioned "bridge phenomenon" is not restricted to the modes shown in FIG. 9, but may occur in various modes in response to relation between the cross-directional size 15 and the sizes of the electronic component chips 4. In other words, this phenomenon easily takes place when the combination of the longitudinal, cross-directional and perpendicular sizes of the plurality of electronic component chips 4 accidentally corresponds may take place not only in response to the relation with the cross-directional size 15 of the small chamber 7 but also in relations with the perpendicular sizes 16 and 17.
The "bridge phenomenon" is not so frequent but merely occurs in the order of p.p.m. in general. Once the "bridge phenomenon" takes place, however, it is impossible or difficult to supply the electronic component chips 4 to the aligning passage 8. In order to improve workability and reliability of a chip mounting apparatus or the like, therefore, it is desirable to substantially zeroize the probability for the "bridge phenomenon".